git: DragonFly_RELEASE_5_4 hammer2 - refactor filesystem sync 4/N

[Matthew Dillon]

commit 46e6dfe5c32d50499e4df44c0e2f53527060fc54
Author: Matthew Dillon <dillon at apollo.backplane.com>
Date:   Tue Nov 13 13:32:33 2018 -0800

    hammer2 - refactor filesystem sync 4/N
    
    * Save synchronized iroot blockmaps for snapshot code, and use them
      in the snapshot code.
    
    * Improve dependency handling and syncq/sideq flagging for
      dependencies.  Also improve the hammer2_inode_t reordering
      code that allows the frontend to continue operating on dirty
      inodes simultaneous with a filesystem sync.
    
    * Move inode deletion into the filesystem sync code (in addition to
      creation), for the same reason.
    
    * Fix lost ref counts in the snapshot code which were causing umount
      panics.
    
    * Stabilization pass on volume flush code.  Since flushes stop at
      inode boundaries, we must properly flush the superroot before
      flushing the volume header.  That is, the flush sequence is:
    
      - flush inodes for PFS  (flushes inode content)
      - flush PFS root inode  (flushes through to inodes)
      - flush superroot inode (flushes through to PFS root)
      - flush volume header   (flushes voulume header to superroot)
    
      Theoretically this allows the filesystem asynchronously write data
      and inodes flushed by the kernel's buffer cache and vnode code
      concurrent with a filesystem flush without messing up filesystem
      consistency, because these asynchronously flushed inodes are not
      included (or have already been flushed) in the filesystem flush that
      is already underway.
    
    * Filesystem consistency still not perfect (using snapshot-debug
      directive to test during heavy filesystem modification loads,
      directory entries are sometimes desynchronized from their inodes).

Summary of changes:
 sys/vfs/hammer2/hammer2.h        |   6 +-
 sys/vfs/hammer2/hammer2_flush.c  |  60 +++++--
 sys/vfs/hammer2/hammer2_inode.c  | 197 ++++++++-------------
 sys/vfs/hammer2/hammer2_ioctl.c  |  18 +-
 sys/vfs/hammer2/hammer2_vfsops.c | 358 ++++++++++++++++++++++++---------------
 sys/vfs/hammer2/hammer2_vnops.c  |  30 ++--
 6 files changed, 368 insertions(+), 301 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/46e6dfe5c32d50499e4df44c0e2f53527060fc54


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